Accessibility is a general term used to describe the degree to which a product, device, service, or environment is available to as many people as possible. Accessibility can be viewed as the “ability to access” and benefit from some system or entity. Accessibility is often used to focus on people's right of access to entities, often through use of assistive technology.
Speech recognition/synthesis devices and software can improve technology access. An example voice interface includes a speech-to-text system (or text-to-speech (TTS) system) that converts speech into text (or text into speech). Other systems are available that may render symbolic linguistic representations like phonetic transcriptions into speech to facilitate voice interfacing. Speech synthesis can be defined as an artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware.